Building Blocks
by AtlantaNova67
Summary: Sherlock and Mycroft have always had a strange relationship. So when Sherlock jumps off a building and Mycroft is left looking back at the pieces that have built his life, he's surprised to find that they don't add up quite like he thought they would. A deep character study on what makes Sherlock and Mycroft's relationship. One-shot.


**A/N: So this is the first Sherlock fanfiction I've ever posted. But not the first one I've written. In fact, I've got a major multi-chapter fic coming, if anyone would be interested. Reviews would be nice; I like to know what people think.**

**Disclaimer: I don't own Sherlock BBC or any of the characters therein.**

**If Moffat or Gatiss felt like sending me the rights in a gift basket though, that would be a completely different story.**

~oO0Oo~

Mycroft had known the morning Mummy had walked in the room carrying a very loud, baby boy that he would never be the same. His mother had tried to give him the baby and he stood up, gently put down his collector edition of Tolstoy, and walked out of the room. For the first six months of the baby being in the world, Mycroft saw him only once.

It had only seemed fitting when Mummy had accidentally forgotten the baby at London International on her way back from Paris that Mycroft step up and keep an eye on Sherlock. The transition was smooth and Mycroft slowly went from awkwardly trying to please his mother to becoming Sherlock's full-time supervisor.

At first, it was dull. All the child did was poop into disposable diapers, scream when he was cranky or needed food, and suck on his thumb. He made sure that he had competent nannies and occasionally visited the whiney nine-month-old. It's not as if the child was an active conversationalist at the time.

He actively started avoiding the child when he realized that his eyes were going to stay blue. It took him three more months, two blood tests and the paternity results to convince Mycroft that the blub of gurgling child that his mother had given birth to was truly his blood brother.

After that, he limited his association with his smaller sibling to almost nothing. The nannies took care of the child and he was content with the arrangement.

* * *

Until one day, the child's favorite nurse ran out of the nursery screaming and swearing. He was given her resignation by the end of the day and the rest of the staff quickly followed. He found himself forced into his brother's company by pure necessity.

The child, as he had always referred to him, was small. However, upon looking up, Mycroft was startled at the intelligent blue eyes that stared back at him. The toddler, who was just approaching his second birthday, looked up at Mycroft and smiled. He ran across the room, picking up a book from a small collection and ran back to Mycroft. He slipped into a chair as the little boy reached him and with a high-pitched giggle pushed the book into his hands and clambered up onto his lap. He was shocked into silence as the toddler wriggled around until he was comfortable and then pounded on the book with his fists.

"Read me." He demanded, little fingers digging at the pages of the book as he tried to open it. He finally gave up in frustration and pushed the book into Mycroft's stomach demanding that it be opened. "Read da book!" He squealed. Without thinking, still in awe of the little person that was now distracted by his watch, Mycroft reached for the book and began to read.

And so (after he found some reasonably competent help to replace those that had left) a tradition began; he found himself reading an extremely illiterate book to a rather chubby toddler every afternoon.

* * *

The day 'the child' became Sherlock was fairly uneventful to the rest of the world. Mycroft had known that the child's name was Sherlock since before he had even come into the world. But he had left this name unspoken for reasons that even Sherlock would never understand. For a long time, he had simply refused to speak his name because it was an old family name and had been passed down for generations and because his reservations about the child's legitimate claim to the Holmes' blood had held him back. But even after that, when he had began to show very prominent Holmes' traits such as the cheekbones and high forehead and startling intellect, Mycroft still refused to call him by his real name.

Mycroft was simply afraid of getting attached.

He knew that the second that he was comfortable enough to call the child by his given name there would be no going back. Even the toddler knew better then to call Mycroft by his given name; it was just a slightly slurred version of 'brother'.

It was unbelievably frustrating when it slipped out one day. The boy had been playing quietly with his toys (which had quickly evolved from trains and cars, to fake microscopes and Petri dishes) when he had gotten up and ran across the room just as Mycroft had walked in. The boy was running full speed for a toy, presumably to show off to his brother, when he lost his footing and tumbled straight into his bed, cracking his head on the railing. He screamed and immediately burst into tears.

Mycroft found his way to the little boy and was already reaching to pick him up when it came out, "Sherlock," he said soothingly, "Sherlock, it's alright."

The little boy stared up at him, dazed, still hiccupping from the onset of sudden tears. Sherlock sniffled and was lifted into Mycroft's arms, snuggling into his chest, sobs still shaking his little body. It took a while before the shock and tears wore off and he was silent.

It was then that Mycroft realized what he had called him. He sighed into Sherlock's black curls and frowned. He was in trouble. His job from the very beginning had been to make sure that Sherlock had a competent staff watching over him and that was it. It had never been his intention to grow attached to him, let alone allow him to wiggle under his well-built barriers.

Sherlock fell asleep in his arms, still sniffling from his crying. His tiny lashes fluttering against his chubby pink cheeks. For a long time, Mycroft just held him, watching his tiny stomach heave with each labored breath.

It had become evident that he was very much in danger of becoming completely infatuated with the creature that lay in his arms.

* * *

Mycroft knew from the moment that Sherlock received the rabbit that things were not going to end well. He doted on the animal. At one point, he literally had to pull it from Sherlock's arms to keep the child from sleeping with it.

Sherlock's capacity to care was more than Mycroft could fathom and he knew that this was not going to go over well with the children at school.

Sherlock was brilliant.

So much in fact, less than a week ago, the boy had run into his office announcing that he was 130 sequences into the Fibonacci Series. He was barely six years old; still clad in his footy pajamas when he had come to announce his progress.

The children at school were going to be anything but accepting of his genius. It didn't help that his high cheekbones and startling blue eyes were already on their way to making him look… eccentric.

Mycroft knew exactly how cruel the schoolchildren could be to those that didn't fit their standard of 'normal'. He had learned those lessons quickly and his mind was already painting very vivid scenarios of the things that would happen if he let Sherlock go to school at this vulnerable age.

His greatest fears about the fragility of Sherlock's heart came true two days later when the rabbit died. The little boy sobbed into his chest for almost an hour, randomly muttering that it was his bestest friend and begging that Mycroft bring it back.

His brother was going to have to grow up if he was going to survive school; otherwise, the first few years would be murderous.

* * *

By the time Sherlock was seven, the book reading tradition had evolved from cardboard books to science textbooks. Mycroft was having a hard time not visibly wincing every time Sherlock found the household cleaning chemicals.

He had known one day Sherlock was going to realize that he was the adult figure and that he might begin to imitate him. It startled him however when he turned around and found the little boy concentrating on a puzzle, hands neatly steepled underneath his nose.

Mycroft sucked in a breath and watched his little face. Brow furrowed in thought, mouth curved in a delicate frown; two expressions far too old for someone his age.

It took him a moment to take in what this development meant.

To have a child so dependent on you that they begin to form their personality around your mannerisms and your personality traits... the thought nearly had Mycroft on his knees with the pure power it brought him. Sherlock looked to Mycroft as his model and anything and everything he did from now on would directly influence how Sherlock dealt with future issues.

The amount of the things he could do with that knowledge was crippling and yet he knew exactly what was he was going to have to do.

There was moment right before he made the decision to go through with his plan, when he knew he should have considered the morals of what he was about to do. But the moment he had uttered Sherlock's name out loud there had been no going back and now all he could do was move forward and hope his little brother turned out better for it.

* * *

Years of training himself to be cold and heartless had been difficult, but it had worked, as Sherlock had slowly begun to imitate him.

When Sherlock walked into his office at twelve-years-old and declared himself a self-diagnosed sociopath, Mycroft was relieved.

* * *

When Mycroft found Sherlock high for the first time, he wasn't particularly worried.

He had taken advantage of Sherlock's innocence when he was small. He'd transformed a little boy that wore his heart on his sleeve into a cold, sharp tongued young man. Someone that could fight back when life got rough. If anything, the child deserved a reprieve from the harsh words of his fellow students.

So he let Sherlock do as he pleased.

* * *

When Sherlock overdosed for the first time, he set up a kind of babysitter. He chose another student from his class that he knew would care enough about Sherlock to keep him from doing anything stupid.

He never expected Sherlock to fall in love with her.

* * *

By this time, Mycroft was well established in the British government. And the CIA and the British Secret Service.

He found that his years of play-acting for Sherlock's benefit proved extremely useful in his government positions and he found himself easily climbing up the ladders of success. His cold, calm exterior had him dealing with national and international problems that would have had other men unraveling within minutes. The power very easily became addicting. People stopped wondering who to call when something blew up; they all had his number on speed dial.

His mother found out about his rising success and ambushed him. She presented him with his father's umbrella. He almost refused the gift. Too sentimental. What kind of an example would that set for Sherlock? His mother glared at his hesitation and he took the umbrella.

It turns out that the umbrella just made people more in awe of him.

Sherlock chalked it up to another power play; just something to go along with the sleek black cars and warehouses Mycroft already seemed to play on. He never suspected that Mycroft kept it around as a reminder of his father.

For a moment, Mycroft was almost proud of his parenting skills.

* * *

Sherlock had just reached the age of twenty when Mycroft began to regret encouraging the sociopathic behavior.

They were twelve years apart. Mycroft had seen more of the world, dealt with more problems, and held more on his shoulders then a 32-year-old should. But when it came to dealing with Sherlock's grief, he was entirely unprepared.

The boy floundered for a while. Floating to being entirely emotionless to being overwhelmed. Sometimes he would stare blankly at the wall for hours. Other times he would be normal, running his experiments, getting on Mycroft's nerves. Sometimes he would follow Sherlock on the CCTV cameras for hours; he would wander around London as if he were searching for something; completely lost and broken.

He knew Sherlock blamed him. That was to be expected.

There was one thing Mycroft Holmes never saw coming though.

He knew that Sherlock could delete things. He had heard him complain that unimportant things cluttered his mind and he needed to erase them.

He had never imagined Sherlock could delete an entire person. Delete thousands of memories, all within the space of several hours. Mycroft suspected it had something to do with the massive amounts of drugs he'd been taking at the time.

It was completely unsettling and for the first time Mycroft began to wonder if he had gone too far. If he had given the sweet little boy an example that was impossible to match and now it was taking its toll.

He prayed for a miracle.

* * *

His miracle came in Florida, nearly eight years later. Sherlock had been switching back and forth between rehab and taking part time cases. Mycroft had never suspected that miracles came in the shape of old women.

She took pity on the young man that had saved her from her mad husband and literally smacked Sherlock Holmes into getting cleaning. And after a fairly harsh dressing down about not being a good enough parent figure, Mycroft was positive that Mrs. Hudson was going to be the death of him.

* * *

John Watson deserved to be knighted.

Mycroft had decided this after his first five-minute conversation with the man. His deductions were confirmed when he found the two of them giggling outside of a crime scene in which it was fairly obvious Dr. Watson himself had shot the perpetrator.

It was also very worrying.

John was clearly attached to Sherlock and judging by his brother's smile as they left the crime scene, the sentiment was returned. Mycroft felt he had reason to be concerned about the two of them.

Very concerned.

* * *

John very easily slipped into what had been Mycroft's old role. He became Sherlock's conscience. The difference was that instead of taking away Sherlock's morality, John was slowly putting it back into place.

Mycroft knew he could do nothing about this process. John was simply too good for Sherlock and he was thriving on having a close friend.

All he could do to keep Sherlock's well-built defenses from crumbling was to feed him verbal reminders of what Mycroft had been engraining into that brain since he was old enough to learn.

_"Caring is not an advantage." _Spoken in the harsh halls of St. Bart's. _"All hearts are broken."_

John Watson was pulling down Sherlock's walls around him and no good was going to come from it.

All he could do was hope that at least something of Sherlock's childhood would stay with him.

* * *

When Jim Moriarty asked for Sherlock's childhood, Mycroft couldn't help himself.

Sherlock was his greatest achievement. What's the point in hiding your prized possession?

* * *

Mycroft sat in the plush seat of The Diogenes Club and knew exactly where he had made his mistake. Sherlock had never been his to mold.

In fact, as Mycroft laid the copy of The Sun down on the tea table and quietly steepled his hands underneath his nose, he knew that really without Sherlock he had no purpose.

It was a startling realization to know that he started marking his achievements from the day Sherlock was born.

Now Sherlock was dead.

Mycroft Holmes simply did not exist without Sherlock.

* * *

**Right, so bad? Good? Tell me what you think.**

**Beta'd by both Sam and Mayan. Thank you.**


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